When people are sleep-deprived, they eat almost 300 calories a day more than when they are well-rested. And ice cream is one of their favorite foods to eat when they're tired, a new study shows.

Scientists have known for years that too little shut-eye can lead to weight gain and obesity.

So researchers at Columbia University decided to find out whether people actually consume more when they are sleep-deprived vs. well-rested.

They recruited 26 normal-weight men and women who routinely slept between seven and nine hours a night. The participants came into an inpatient hospital-like setting for six days on two different occasions. Half slept four hours a night for six nights. The other half slept for nine hours a night for six nights.